Ranked among the leaders of photography from the late 1920's through the 1960's Mckay was an inventor, teacher, author, columnist, technical expert and scientist. He brought to his chosen field (3d photography) a penetrating analytical mind and a scientific approach. 

  In 1924 McKay authored the first book on amateur 16mm cinematography.  He was the first person in this country to conduct a radio program on photography. (WEAF in 1928)

  As a columnist (American Photography, U.S. Camera, and many others), he wrote one of the longest-appearing photographic columns in the country.  He was one of the first to introduce 35mm photography into the United States, writing the first American published booklet on Leica Photography.  As one of the organizers of he Stereo Guild in 1949 he continued to provide leadership and expert guidance to 3d photographers world wide.

   An avid microscopist and researcher, he contributed to several scientific journals and made some of the earliest photomicrographic movies.

  He moved from New York City to Eustis, Florida in the mid 1940's and continued to write  until his death in 1971.